If a devout Christian from the year 1000 A.D. were to be dropped into a mid-morning service at a 21st century progressive church, the medieval Christian wouuld not recognize the Christian faith, says Kevin Kelly in the latest issue of Willow magazine – a publication of the influential Willow Creek Community Church.

So it's "reasonable and responsible to expect tremendous change in the Christian church" in the next millennium, he writes.

Besides the end of the world happening in this lifetime, Kelly offers five other scenarios – or plausible stories – for what the church may look like in the year 3,000 A.D.

And he cautions, "If Christians don’t seize the future, then unbelievers will."

Scenario One

The center of Christianity will continue to shift west. Since the time of Christ, the center of gravity for the global Christian church has steadily moved west from its epicenter in Jerusalem. It has shifted to Armenia, Greece, Rome, then into Europe, and further west into North and South America.

Many reports indicate that the center of Christianity is now in Asia and Africa where the Christian population is booming.

But Kelly says it won't stop there.

"If the move west continues as it has for the last 2,000 years, Christianity’s center of gravity will keep migrating westward beyond East and Central Asia. The new missionaries based in Asia in the coming century will reach out to unbelievers in the birthplace of Christianity."

Eventually, the epicenter of Christianity will circumnavigate the globe and arrive back where it began in Jerusalem.

That means, "unless Christianity in the U.S. becomes less parochial and more global, what happens in North American Christianity in the next 500 years may simply be the side-show," Kelly writes. "The main event will happen elsewhere around the globe."

Scenario Two

The varieties of Christianity, including the number of creeds and denominations, will continue to increase. Christian denominations have increased from 500 in 1800 to 40,000 in 2007, Kelly cites.

And nothing will apparently halt the diversification.

"When you can get 72 varieties of mustard in the supermarket, choice is accepted," he writes. "There is no known counter force visible in our culture which would work against increased varieties in Christian approaches."

Scenario Three

Churches outside mainstream Christianity are growing the fastest. The greatest growth in the future is expected from such marginal church groups as the Mormons and the Amish.

The growth, however, won't go without criticism. These churches will be, and some already are, considered cults or heretics by the orthodox, Kelly points out.

Nevertheless, Kelly says "an entirely safe bet would be that the largest denomination 1,000 years from now is one that does not exist at the moment."

Currently, the largest church in the United States is Lakewood Church, a nondenominational church of now 40,000 weekly attendants, in Houston. It was founded in 1959.

Scenario Four

An overwhelming majority of the challenges – such as abortion, stem cell therapies and pornography – Christianity will be facing in the next millennium will be driven by new technologies. Kelly points out that today's challenges are tame compared to the ones coming.

And as Christians have already been witnessing, the next generations of Christians will speak the Facebook and YouTube language as easily as Americans speak English today.

"The long-term trend is more technology in the Christian culture; what is missing, and what may take several generations to supply, is an understanding of the spiritual meaning of technology," Kelly writes.

Scenario Five

As culture continues to move toward a future of questioning and doubt, Christianity has to "develop a cultural practice of positive questioning, of active holy doubt, and a clear articulation of what is eternal and what is in flux," he notes.

That practice is likely to be constructed not by theologians, Kelly says, but by members of the worldwide church in a distributed social media context. "The wiki-church."

And that includes Muslims.

The Christian community is shrinking in Europe while the Islamic community continues to grow. And while Islam has turned radical and militant in other parts of the world, Kelly points to the millions of non-militant moderate Muslim communities.

"On many social issues moderate Islam and conservative Christianity agree," he contends. "They are both people of the book. They both honor many of the same prophets. They agree on many religious issues like prayer, sexuality, sin, and family.

"It is not impossible to imagine Muslims and Christians becoming allies in the inevitable culture wars of the future. It is no more impossible than imagining Christians and Jews would be allies a thousand years ago."

Kelly predicts 100 years from now, a conservative Christian-Islam alliance might be a serious global political force.

While none of the five scenarios may happen, they are presented in order to gain a firm grasp of the present trends, Kelly says.

"Sometimes it takes an exercise of extrapolating to a thousand years from now to see what is happening tomorrow. Only by extending a trend can we see if it might endure, or survive in the face of other trends, or if it might provoke an awareness of a trend we could not see before."